Scientists from Alberta Geological Survey and the University of Alberta have discovered an 8 km wide bowl-shaped impact crater near Bow City in southern Alberta.
This map shows the location (orange point) of the newly discovered impact crater near Bow City, southern Alberta. Image credit: Shaund / CC BY-SA 3.0.
“We know that the impact occurred within the last 70 million years, and in that time about 1.5 km of sediment has been eroded. That makes it really hard to pin down and actually date the impact,” said Dr Douglas Schmitt of the University of Alberta, a co-author of the paper published in the journal Meteoritics & Planetary Science.
“Time and glaciers have buried and eroded much of the evidence, making it impossible at this point to say with full certainty the ring-like structure was caused by a meteorite impact, but that’s what seismic and geological evidence strongly suggests.”
Erosion has worn away all but the roots of the crater, leaving a semicircular depression with a central peak. When the crater formed, it likely reached a depth of 1.6 to 2.4 km.
Outcrop photographs from the Bow City crater: top – panoramic view; bottom – a close-up showing thrust faults, outlined in red; geologist kneeling on outcrop, black arrow, for scale. Image credit: Paul Glombick et al.
“An impact of this magnitude would kill everything for quite a distance,” said Wei Xie, a graduate student at the University of Alberta and a co-author on the study.
“If it happened today, Calgary (200 km to the northwest) would be completely fried and in Edmonton (500 km northwest), every window would have been blown out.”
“Something of that size, throwing that much debris in the air, potentially would have global consequences; there could have been ramifications for decades.”
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Paul Glombick et al. The Bow City structure, southern Alberta, Canada: The deep roots of a complex impact structure? Meteoritics & Planetary Science, published online April 29, 2014; doi: 10.1111/maps.12296
Source link: https://www.sci.news/geology/science-bow-city-impact-crater-canada-01913.html
